Art is both physical and metaphysical. It is metaphysical first: conception. It is physical second: expression. It is concept as expressed in a physical medium -- or mediums.
Poetry is expressed as concepts in sound. (Mind)
Graphic art is expressed as form:
Visual (Sight)
Sculpture (Touch)
Music is expressed as sound, rhythm, and reach. (Sound)
Dance is expressed as motion and movement.
Gastronomy is expressed as food (Taste)
Architecture is expressed as environmental engagement. (Buildings and lansscapie)
Theatre is expressed as existential forms of all of the above (Sets and people on stage in plays performed).
Religion is expressed by the numinous nature of spirit. (In worship, embodied in liturgy, sacraments and sacramentals)
These each share features with the others, but each has its own identity, as defined by its focus on a medium and frame (or proscenium) appropriate to that medium. Some – numbers 5, 6, 7, and 8 – combine forms.
Yet, in the end, art is not the medium, but rather the concept that the artist is trying to express through a medium. It can usually be expressed in any of the other arts, and often is!
So when art is on display – on the wall of a gallery, as a sculpture in a courtyard, in the reading of a poem, or the playing of a score – it is always important to ask oneself, "What am I witnessing? . . . What is the metaphysical reality that is actually on display here?"
These are questions that poetry is often quite literally, verbally answering. Keep in mind, art happens in perception, not only of human artifacts but of the "reality" we witness at every moment of every day. Most of us . . . all of us most of the time . . . do not try to express it by creating an artifact, as does the artist . . . occasionally. The point here is that the art is found in the perception of the artist, the artifact results from the craft of the artist.